1. Field of the Invention
The present invention relates to hardware and software configurations of communication apparatuses (at the base station and terminals) for processing data communicated over a plurality of channels. It is particularly suitable for communication apparatuses for use in mobile communication systems using code division multiple access (CDMA).
2. Description of the Related Art
The configuration of a base station for use in CDMA mobile communication systems according to the prior art is shown in FIG. 12.
Received signals of a carrier frequency band received from an antenna 100 are converted into received baseband signals by a radio frequency block 101, and inputted to a baseband block 134. Baseband transmitted signals of different channels outputted from the baseband block 134 are superposed by an output multiplexer 107, converted by a radio frequency block 101 into transmitted signals of the carrier frequency band, and transmitted from the antenna 100.
The baseband block 134 is equipped with as many modulator/demodulators 102-104, each for processing transmission and reception over one channel, as the channels used by the base station. A matched filter (MF) 135 and a peak detector 136 are jointly provided for a plurality of channels, and intermittently perform path searching for each of the channels. Each peak detector 136 selects the higher peaks of correlation values outputted from an MF (indicating the multi-path reception timing). The selected path timing is set in n correlators such as correlators 108-110 (n is the number of fingers) of one of the modulator/demodulators 102-104 for the corresponding channel to undergo despreading on a finger-by-finger basis.
By executing path search for each channel at the base station periodically on a time division basis in this way and providing one MF jointly for a plurality of channels, the gate size of hardware is reduced. However, in this configuration, a modulator/demodulator 102 is provided for each channel.
Also, as a communication mode in mobile communication systems, there is the multi-code transmission mode which realizes transmission at high overall speed by multiplex transmission of data to be transmitted using a plurality of low-speed transmission channels. Where a mobile station is to support this multi-code transmission mode, its baseband block is required to have number of modulator/demodulators corresponding to a plurality of channels as in the base station shown in FIG. 12.